I have an interesting issue.
I use the AFE as a front end to a 3 channel CIS head. I am running in Sample/Hold mode, and master mode and SH_R is unconnected. Coarse and fine turning of the Pixel phase is done, to uptimize the position of the clamping.
Now when I scan a white sheet of paper I get something strange.
Lets say I scan at the left (channel 1). The paper covers the full channel, and a bit of channel 2.
The median value of the white pixels in channel 1 is around 120.
The few pixels that are white in channel 2 have a median value of 200.
Now if I make a second scan where I place the white paper at channel 2, the "white" pixels have a median value of 120, while the few pixels in channel 1 and 3 are 200.
If I place the paper half/half the median value is around 160.
I have measured the input to the AFE, and it is stable.. it does not change its level depending on the number of pixels that are convered.
Is this issue known and help to point me in the right direction is highly appriciated